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Warsaw 2017
DVH Reduction
• Power Law gives a relationship between
Dose and fractional volume while keeping
the NTCP constant
• As a result we can transform the DVH
by…
– Converting bin doses to an equivalent
dose to the whole organ (D
eff
method)
OR
– Converting bin volumes into volumes
for a particular reference dose (V
eff
method)
• Then: Substitute V
eff
or D
eff
into Lyman
Equations to get NTCP as dose is now
uniform to organ
Two methods to get a single
number to represent a DVH
As a very simple
demonstration, a two-
step DVH is reduced to
one step:
Kutcher & Berman:
effective volumeat
maximumdose, V
eff
Lyman & Wolbarst:
effectivedose to whole
(or reference) volume,
D
eff
Assumes each dose bin obeys Power Law
Uniform irradiation to each dose bin